Quinone, aldehyde and chrome tanned articles and their production



Jan. 19, 1965 R. L. KRONENTHAL QUINONE, ALDEHYDE AND CHROME TANNED ARTICLES AND THEIR PRODUCTION 2 Sheets-Sheet 1 Filed May 29, 1965 INVENTOR. f/owwliawwdfm/vz/mw Jan. 19, 1965 R. L. KRONENTHAL 3,166,073

QUINONE, ALDEI-IYDE AND CHROME TANNED ARTICLES AND THEIR PRODUCTION Filed May 29, 1963 2 Sheets-Sheet 2 INVENTOR. flat/V420. 150M420 lfivaMs/vr/az BY yb/ I it TTGAA EYSJ Q'UTNGBE, ALBEHYDE AND CHRGNE TANNED ARTIQLES AND THEHR PRGDUCTTON Richard Leonard Kronenthai, Fair Lawn, Ni, assignor to Ethicon, Inc, Somervilie, NJL, a corporation of New Jersey Filed May 29, 1963, Ser. No. 284,209 14 Claims. (Ci. 123-3355) The present invention relates to the treatment of protein materials and 'the product so obtained with particular emphasis on the method of chemically treating substantially pure collagen filaments and strands for surgical uses such as suturing and ligating.

This application is a continuation-in-part of application Serial No. 85,289, filed January 27, 1961.

For the sake of clarity, the terms used herein are defined as follows: 7 f

The term tendon collagen fibril as used herein means a thread-like collagen structure derived from beef tendon that is round in cross section. These fibrils in the cornpletely dehydrated state measure Angstrorns in diameter.

The term swollen tendon collagen fibril as used here in means a collagen fibril derived from beef tendon that has been swollen in acid solution. The diameters of swollen collagen fibrils range from less than 5000 Angstroms to about 90,000 Angstroms. i

The term monofilament as used herein means asingle thread of oriented collagen fibrils as extruded through a single orifice in a spinnerette.

The term strand as used herein means a group of filaments that have been united to form a unitary structure.

The term multifilamen as used herein means a group of individual separate filaments extruded through a spinnerette.

about 500 toZOOO The protein collagen has exceptional tensile strength and.

is essentially non-antigenic, which properties have resulted in the wide use of substantially pure collagen strands in surgery. It is well known that collagen sutures which have been implanted in the human body are slowly attacked by proteolytic enzymes with a resulting decrease in tensile strength and ultimate absorption. It is also known that the rate of absorption can be controlled by treating the collagen strand with chemical reagents such as chromium salts. Thus, chromium treated sutures have been prepared from sheep intestines which retain onehalf of their original tensile strength from 7 to 10 days after implantation. i

A particular problem exists, however, in the case of extruded collagen strands. It has been noted that collagen strands obtained by extruding a dispersion of coilagen fibrils into a coagulating bath are characterized bya rapid in vivo digestion. Thus, a collagen suture prepared under conditions that involve swelling collagen fibrils in acid solution, extruding the swollen collagen fibrils to form a filament and subsequently dehydrating the swollen collagen fibrils is more rapidly attacked by proteolytic enzymes than sutures prepared from sheep intestines.

It is an object of the present invention, therefore, to chemically modify collagen and thereby increase its resistance to enzymatic degradation.

It is another object of the invention to provide a chemically treated collagen suture having a suitable Wet tensile strength.

Still another object of the invention is to produce an extruded chemically treated absorbable collagen suture that will retain sufiicient tensilestrength under the conditions of use to accomplish its purpose and be absorbed in the body after the wound has healed when the suture is no longer necessary. 7

. The present invention provides a method of chemically treating a continuously extruded collagen strand to provide the'desired strength, in vivo digestion time and uniformity of product. The process is characterized by treating a bonded collagen multifilament consecutively with at least two different solutions. The first solution is asolution'of apoiyhydric phenol such as pyrogallol and/ or an oxidized polyhydric phenol such as 1,4-naphthaquinone and the second solution is an acid solution of .a chromium salt and an aldehyde such as-formaldehyde. The use of a third solution containing an alkaline solution of formaldehyde to treat the moving strand is optional. I

The first solution of polyhydric phenol and for quinone, if used alone, provides a collagen strand which has inadequate initial wet strength and which has an excessively rapid rate of in vivo tensile strength loss. However, when this treatment is followed by the second solution containing formaldehyde, the said rate is decreased. It is known that formaldehyde alone will increase the initial wet strength of collagen, but if formaldehyde alone is used in the amount required for adequate in vivo properties,

. tensile strength loss of the collagen at the concentrations employed in the-present invention. 7

It will be understood by those skilled in the art that equivalent results would be obtained if the order of solutions Were reversed and the collagen was first treated with a chromium formaldehyde solution and then treated with the polyhydric phenol and/ or quinone solution. Also,'the formaldehyde and chromium can be applied separately in different solutions.

The invention will appear more clearly from the following detailed description when taken in connection with the accompanying drawings, which show by way of example, preferred embodiments of the'inventive idea.. Referring now to the drawings, 1 6

FIGURE 1' illustrates'a machine designed to continuously tan a bonded collagen multifilamenth FIGURE 2 is a detailed perspective view of a part of the machine illustrated in FIGURE 1" showing the godet 21 which takes up the tape from the supply reel. This figure also shows the auxiliary roller 31 which is as sociated with the godet 21.

FIGURE 3 is a perspective view of a false twister which about 500 individual collagen monofilaments. Collagen Patented Jan. 1 9,

bath. The multifilaments, as they emerge from thespin bath, are very loosely united and are approximatelycircular in cross-section; however, the filaments are drawn from the spin bath by a rotating godet and the tension on the still wet filaments as they pass over the godet surface bonds the individual filaments together to form a ribbonlike strand. When the bonded multifilament is dried, the ribbon-like shape is retained. It will be understood from the foregoing that the individual filaments are bonded together by cohesive forces to form the collagen tape.

The mechanical handling of the collagen tape as it passes through the different tanning solutions and is dried and rounded to form a strand of circular cross-section is best illustrated by FIGURE 1. The machine to be described has been designed for the'continuous treatment of collagen tape containing about 195 filaments and shaping the tanned multifilament to form a rounded strand about 14.5 mils in diameter, but it will be understood that strands of smaller or larger diameter may be produced by varying the number of individual filaments in the collagen tape and such modifications are wellwithin thescope of this invention.

cut time, the upper limit of stretch appears. to be about 20%.

The moving collagen tape may be continuously treated at godet 21 and godet 22. The solution 41 in the tray 14 may be an alkaline aqueous solution of a polyhydric phenol and/or quinone such as pyrogallol; resorcinol; hydroquinone; 2,2',4,4-tetrahydroxybenzophenone; 1,2 naphthoquinone; 1,2-naphthoquinone-4-sulfonic acid s0- dium salt; 1,4-naphthoquinoue; p-toluguinone, 1,2-anthraquinone; or mixtures of these compounds. Polyhydric phenols and quinones that are most effective in the tan ning process of the present invention are those which have an unsubstituted position adjacent to the oxygen function.

It will be noted from FIGURE ,1 that the collagen tape 7 11 is transferred from the supply reel 12 to the takeup spool 13 by the driven godets;21,-22 and 23. The tape is stretched between godet 21 and godet 22, and is stretched again between godets22 and 23. Directly below each godet are auxiliary nylon rollers 31, 32 and 33. The rollers 31 and 32 are surrounded by trays 14 and 15 which may be filled ,with liquids 41 and42 that are to be applied to the moving collagen strand, Other means of treating the moving collagen strand with liquids are providedby the jets 20, 24 and 25. l The tubes 16, 17 and Bare heated and function to dry and warm the moving strand. The desired circular cross-section of the final product can be accomplished by means of a false twister 19 which operates to round and dry the strand as it moves through the drying tubes .17 and 18.

The three godets 21, 22 and 23 may be made of nylon and each is preferably 3 inches in circumference. All three godets are driven by a Reeves variable speed gear reductionmotor having an output speed range of 3.3 to

32.1 r.p.m. Directly below godet 21 is an auxiliary nylon roller 31, as best shown in FIGURE 2. The separation of the collagen tape on godet 21 is controlled by moving the axis of the auxiliary roller 31 with respect to the axis of the godet. The roller 31 pivots on the hinge pin 26 and may be securely fixed in any position by the set screw 28.

The godet 21 is driven at a speed of about 10 rpm. At 10 r.p.m., the linear rate of tanning is about 30 inches per minute. The collagen tape from a tensioning device 35 passes three times around godet 21, the three loops providing sufficient time in the bath 41 to Wet out the collagen tape well with the tanning solution.

Godet 22 is driven at 11 rpm. and, thereforgproduces a 10% stretch in-the tape between godet 21. and godet 22.' The'amount of stretch in this stage may-be increased or decreasedv by varying the relationship be-' tween the speedsj of godet 21 and godet 22. It will be noted that the strand iswrapped around godet 22 three times. 'The stretching between godet 21 and godet 22 provides orientation of the drying'collagen tape and improves the tensile strength. i i

. Qonditions'may, for example, be controlled sothat the godet 21 is operated at 10 r.p.m., godet 22 1s operated'at l1 r.p.m., and godet 23 isoperated at 12 r.p.m. Under these conditions, one would obtain, in addition to the 10% stretch between godets 21 and 22, another 10% stretch between godets 22 and 23. The overall stretch may be varied from about 10% to and at the preshave poor dry knot strength.

In addition to the polyhydric phenol'or quinone, the solution 41 may contain a small amount (about 0.5%) of a chelating agent, i.e., the disodium salt of ethylene diamine tetraacetic acid, to associatewith any metal contaminants. A strong reducing agentsuch as formaldehyde sodium sulfoxylate (marketed as Formopan), about 0.1%, can be used in the bathto deter oxidation.

The concentration ofpolyhydric phenol-and/ or quinone in the bath 41 is from about 0.2% to about',2.0% and the preferred polyhydric phenol is pyrogallol. If this bath 41 is acidic or neutral the collagen tape will pick up too much water. It is helpful, therefore, to adjust the pH of this bath to about 7.510.5 with an alkali such as ammonium hydroxide or sodium hydroxide. Excellent results have been obtained when the pH of this tanning bath is 8.3.

The. collagen tape passes from the tanning bath 41 around the idler pulley 30 and then through the drying tube 16. This drying tube has a cross-sectional area of about 2 to 3 square inches and is about 16 inches in length. Air, heated to about 150 F. is circulated through the tube 16 at the rate of about 600 cubic feetper minute.

The driedcollagen tape from the tube 16 passes over an idler pulley 29, is Wrapped three times around godet 22, andis wet out in the second tanning bath 42. The bath 42 contains a basic trivalent chromium saltsu'ch as chromium (III) sulfate or chloride, the sulfatebeing preferred. Bath 42 also contains an aldehyde such as: formaldehyde; acetaldehyde; furfural; glyoxal; succindialdehyde; malonic dialdehyde; glutaraldehyde; etc. Formaldehyde is preferred. For example, bath 42 contains an aqueous solution of chromium (III) sulfate and an aldehyde such as formaldehyde or glyoxal, or mixtures of the two. The concentration of chromium as chromic oxide is about 10 grams per liter, the concentration of formaldehyde and/or glyoxal is about 0.10% to about 0.32% and the pH of the bath is about 2.0-3.5 (unbufiered). If the amount of aldehyde is greater than about 0.32%, the tensile strength of the strand drops and if the amount of aldehyde is ,less than about 0.05%, the in vivo absorption of the strand will be rapid. 1 In passing through this bath, the collagen tape absorbs about 1% by weight of chromium as chromic oxide. It has been noted that the optimum wet tensile strength and dry knot strength of the finished strand is obtained when the amount of chromic oxide in the strand is about 1.0% by weight.v Collagensu'ands (size 2/0) containing less than 0.5% chromic oxide have a low wet tensile strengthand strands containing more than about 1.5% chromic oxide The collagen tape passes fromlthe bath 42 around the idler pulley 34 and through the drying tubes, 17 and 18.

" These tubes have a cross-sectional area similar to that of Air, heated to shaped by contact with a false twister 19 of the type illustrated in FIGURE 3. This device automatically imparts a so-called false twist to the strand, 'a false twist being a twist whose direction on one side of a point of contact is reversed on the opposite side, thus cancelling the twist. The twisting cycle is most effective when the collagen tape is in the wet state, and this may be controlled bydripping water on the tape from the jet 20. The strand may also be lubricated just prior tocontact with the false twister with distilled water which is added through the jet 24. When the twist backs up to the pulley 34, as the wet tape emerges from it, a gradual tapering effect of the strand takes place, which rounds it out. The circular shape of the strand'remains after the twist is cancelled. The false twister is operated in the range of 150 to 1000 rpm.

It is important that the water added through the jet 20 and the velocity and temperature of the air in the drying tube 17 and 18 be controlledso that the wet tanned tape is sufficiently dry when the strand contacts the false twister 19 to avoid deformation. This results in an improved circular cross-section.

The round collagen strand asses from the false twister 19 around the idler pulley 36 and may contact with a solution from the jet 25 flowing downwardly in a direction in which the collagen strand is moving. solution from jet25 is an aqueous solution of from about 0.08% to about 0.3% formaldehyde adjusted to a pH of about 9. If the concentration of formaldehyde is less than about 0.08% or if the tanning at jet 25 is eliminated entirely, the finished collagen strand will be absorbed more quickly when implanted in body tissues.

If the concentration of formaldehyde is greater than about 0.3%, the finished collagen strand will he brittle and have poor dry knot strength.

The wetted out strand from the jet 25 passes through the drying tubes 18 and 17 around theidler'pulley 38 and returns through thedrying tubes 17. and 18 around idler pulley 40. When the godet 23 is operated at 12 r.p.m. to produce about stretch between godet 22 and godet 23, the tension on the finished strand as measured by the tensiometer 44 is about 1500 grams. The dry tanned and rounded strand is removed from the godet 23 by the takeup spool 13 at about 36 inches per minute. The final strand, under the operating conditions described above, has a diameter of about 14.5 mils (sutures size 2/0). v a

It has been observed that atmospheric humidity, a variable during the spinning of a strand, plays an important part in the stretch and the final tensile strength of the strand. The humidity is preferably controlled by en-' casing the spinning operation within the smallest practical enclosure into which the air of controlled humidity may be introduced. Superior uniform strands may be obtained when the relative humidity is maintained at about 40% The continuous processing of collagen tape to obtain a unitary strand of outstanding propertie will be illustrated by the following examples. By way of contrast, several additional examples are provided to demonstrate that tanning of collagen with individual reagents, namely, a chromium salt, formaldehyde and quinone, results in products having in vivo strength unsatisfactory for a surgical suture. Throughout the specification, all quantities are expressed in parts by weight unless otherwise indicated.

EXAMPLE I of deionized water is adjusted to ,pH 2.7 with sodium hydroxide and placed in the tray 15 (bath 42). H

A solution of 0.16 partof formaldehyde and 99.84

parts of deionized water is adjusted to pH 9.0 with ammonium hydroxide and placed in a reservoir feeding the jet Z5. 7 Deionized water is fed to the drips at the top of the drying tube (jet 20) and the top of the twister (jet 24 The collagen tape 11 fromv the 'tensioning device. passes to the godet 21 and'is wrapped three times around the godet and idler 31, the latter being immersed in the bath 41. It takes approximately fifteen seconds to travel one'wrap .so that the total exposure to the solution 41 is about 45 seconds. Thepyrogallol treated strand then moves into the drying tube 16 and is subjected to a current of warm air heated to 60 C. The partially dried strand from the tube 16 then passes over the idler The i pulley '29 and is wrapped-three times around godet 22 and auxiliary roller 32. At this'time, the moving'strand contacts the solution 42 in container 15. a

From the solution '42, the strand travels to the top of the drying tube 17 where it contacts a stream of deionized water dripping tom the jet 20. This serves to saturate the strand with water for better bonding dur-' ing twisting and also helps to remove excess chromium salts. As the strand moves downwardly through the drying tubes 1'7 and 1%, it meets a countercurrent stream of warm air at about 60 C. and is twisted by the false twister 19, which is rotating at approximately 300 rpm.

Just before the strand enter the false twister, it is lubricated with deionized water from the jet 24. This prevents abrasion during the untwisting process. The now rounded strand is next washed with the alkaline formaldehyde solution from jet 25 .and finally dried by a double passage through the drying tubes 17- and 18.. The I v finished strand is taken upon the godetZS, five to ten EXAMPLE n A collagen tape approximately 4 mils thick and 60 mils wide containing 192 individual filaments is processed on the apparatus illustrated in FIGURE 1. The speed of the godets 21, 22 and 23 is maintained at 7.0, 7.7 and 8.3 r.p.m., respectively.

The following solutions are used:

, S0lutz'0nn41 at godet 21 Parts Resorcinol 0.6 Deionized water 99.4

Mixture adjusted to pH 10.3 with ammonium hydrom'de.

Solution 42 at .godet 22 t Parts Chromium (HI) sulfate (as chromic oxide) 0.8

Formaldehyde i 0.24

Glyoxal 0.32

Water 99.36

Mixture adjusted to pH 3.5with sodium hydroxide.

Solution dripped on strand from jet 25 p 1 Parts I Formaldehyde 0.32

Deionized water 99.68

Mixture adjusted to pH 6.0.

; above.

' ionized water.

7 The tape waswrapped six times around godet 21, five times at godet 22 and nineitimes around godet 23. In all other respects, the conditons of Examples II were identical with those described in Example I above. The properties of the product so obtained are summarized in Tables'I and H. i EXAMPLE III 1 .A suture material is prepared exactly as describedin 7 Example II above, except that thesolution 41 at godet 21 is a solution of 0.6 part of hydroquinone dissolved in 99.4 parts of deionized water. The pH of this solution is adjusted to 10.3 with ammonium hydroxide. The

properties of the product so obtained are summarized in Tables I and II.

EXAMPLEIV A strand is prepared by the method described in Example I. The following solutions are .used:

Solution 41 at godez 21 Water at pH 10.3 (ammonium hydroxide).

Solution 42 at godet 22 Mixture adjusted to pH 5.6 with sodium hydroxide.

The strand so obtained is then immersed for one hourin a solution of 1.0 part p-bcnzoquinone and 99 parts of distilled water. The strand is rinsed in acetone and air dried. The properties of the product so obtained are summarized in Tables I and II.

EXAMPLE v Parts A strand is prepared by the method described in Ex I ample I, using solutions as described in Example IV The strand so obtained is then immersed for one hour in a solution containing 1.0 part of 1,2-naphthoquinone-4-sulfonic acid sodium salt and 99 parts of de- The strand is then rinsed inacetone and dried. The product so obtained has cated in Tables I and II.

9 EXAMPLE v1 Extruded collagen multifilament was tanned in a basic chromium sulfate bath containing 1.25 percent Cr O No formaldehyde or quinone was used in the tanning process. Properties of the product are set forth in Tables I and II.

EXAMPLE VII Extruded collagen multifilament was tanned in a bath containing 0.15 percent formaldehyde. No chromium or quinone was used in the tanning process- Tables I and II reveal properties of the product so obtained.

' EXAMPLE V111 Extruded collagen multifilament' was tanned in a bath containing 0.5 percent quinone. No chromium or formal: dehyde was used in the tanning process. Propertiesof the product are shown in Tables I and II;

EX MP 1x1 the properties ind i-.

Properties of the result- '3.5 in bath 42.

0.5 percent of quinone used in Example VIII; 0.5 percent of quinone, followed by 1.0 percent of CH0: and 0.3 percent of formaldehyde, in Example IX.

TABLE II [In vivo absorption in pounds] 7 Days Implanted Example (only Cr) VII (only HCHO) VIII* (only quinone) IX *0.5 percent of quinone used in Example VIII; 0.5 percent of quinone, followed by 1.0 percent of ClzOa and 0.3 percent of formaldehyde, in

Example IX.

- EXAMPLE X Another series of experiments was carried out to determine the separate effects of chromium sulfate, quinone and formaldehyde upon an extruded collagen tape. Each reagent was applied by the procedure described in Example I, above. In experiments 1 through 3, quinone was applied from the bath 41 and distilled water adjusted to pH 3.5 was applied from the bath 42. In experiments 4 through 6, distilled water at pH 8.3 was placed in bath 41 and formaldehyde at pH 3.5 in bath 42. In experiments 7 through 9, distilled water. at pH 8.3 was placed in bath 41 and chromium sulfate at pH 9 In all experiments, lactic acid was eliminated from bath 42, jets 20 and 24 were not. used and the strand was wet out with an aqueous solution of 0.3 percent formaldehyde (pH 8.5) at the jet 25. The following results were obtained Compound pH Levels of Treatment Experi- Bath ment No 1. Quiuone 1, 2, 3 2. Formaldehyde 4, 5, 6 3. Chromium sulfate- 7, 8, 9

Tensile strength (pounds) Sample Tanning Treatment Denier Dry Dry Wet 1 N o. Straight Knot 0t;

' 1, 10. 3 5.0 2. o 1, 9. 7 5. 1 2. 0 i 1, 10. 9 4. 7 2. 1 .5- 1,100 9. s 4. 5 2.8 0 6% H0110, pH .5 1, 120 10.1 4. 2 2. 9 6 1.5% HCHO, pH 3.5 8. 2 44. 1 2. 6 7--- 1.0% CI2(SO4)3 9.4 5.6 2.9 10. 3 5. 3 4. 2 9 12. 4 5. 9 4. 6

Sutures prepared according to the method of the present invention .contain polyhydric phenols and/ or quinone reduction products that are chemically combined with the collagen. A quantative determination of the amount of polyhydric phenol or quinone that is present in the finished suture may be made by the following method.

A IO-milligram sample of a polyhydric phenol and/ or quinone tanned suture isplaced in a test tube and l milliliter of sodium borohydride solution is added. The solution of sodium borohydride is'prepared by dissolving 0.60 gram of sodium borohydride in 20 milliliters of disstilled water and adding one pellet of sodium hydroxide. This solution is prepared fresh for each group of samples. The test tube containing the suture to be analyzed and borohydride solution is heated over a Bunsen flame until the suture is dissolved. The contents of the test tube are then neutralized with concentrated sulfuric acid and the test tube is heated to decompose any excess sodium borohydride solution. The reaction mixture so obtained is cooled and diluted to 3 milliliters with distilled water. One milliliter of a vanillin reagent, prepared by dissolving 7.5 grams of vanillin in 50 milliliters of ethyl alcohol, is added and the mixture is diluted with 79% sulfuric acid to 23 milliliters. After 20 minutes, the absor-bance at 520 mu is compared with a reagent'blank using a Beckrnan'DU. spectrophotometer and four standards containnig 0.01, 0.02, 0.03 and 0.04 milliliter of the cooled, 5 rnls. of ethanol are added thereto, and the 1Q chloric acid solution (2 vN) are added to the tube. The tube and its contents are heated over a Bunsen flame until the suture is dissolved. The contents of the tube are resulting solution is shaken. The solution is transferred to a 25 ml. volumetric flask and is made up to volume with distilled water. The resulting solution is filtered into a 50-ml; beaker. Ten milliliters of the filtrate are added to a 25 ml. volumetric flask, whereupon 1 ml. of pyrogallol solution (1% in water) and 10 ml. of ethanol are added. Distilled water is then added to the 25 ml. level of the flask. "After one hour, the absorbance at 425 mu is compared. with a reagent blank using the said spectrophotometer and three standards containing 0.01,

polyhydric phenol or quinone subject of the analysis, such as a pyrogallol solution, prepared by dissolving 0.130 gram of pyrogallol in 4 N sulfuric acid to a total volume of 100 milliliters.

The absorbance values are plotted against the-volume of standard and the percent polyhydric phenol or quinone in the sample is calculated according to the formula K AX 100 Sample weight (mg) in which A is the absorbance obtained from the curve and K, for the 0.04 milliliter standard, is 0.052 milligram pyrogallol divided by A from the curve;

The following list of polyhydric phenols and quinones has also been analyzed by this procedure. In this list, the visible wave length at which maximum absorption Accurate and reproducible results are obtained with the foregoing procedure with phenols and with quinones, with the exception of benzoquinone. A separate procedure is followed in determining benzoquinone content of a suture obtained in accordance with this invention. A SOO-milligram sample of a benZoquinone-tanned suture is placed in a test tube. Five (5) milliliters of hydro- 0.02 and 0.03 milliliters of a benzoquinone standard solution. The standards are prepared by dissilving milligrams of benzoquinone in 100 milliliters of distilled water. The absorbance values are plotted against the volume of the standard and the percent benzoquinone in the sample is calculated according to the formula: Percent benzoquinone:

' Density reading at 425 roux Factor weight of sample (mg) milligrams of benzoquinone absorbing unit Factor I have found that sutures prepared by the method of shown therein, the products obtained therein contain" substantially larger percentages of quinone thanabout 0.25% to about 0.92%, characteristic of the sutures of this invention.

EXAMPLE XII Eirtruded collagen tape, in the form of six strands each of about 6 feet in length, was immersed in a bath con taining 4 liters of an aqueous solution of p-benzoquinone (2% by weight) The pH of the solution was adjusted to 8.0 with ammonium hydroxide in order to completely dissolve the quinone. The strands were so immersed: fora 24 hour period. The strands were then removed from the bath, were washed with demineralizcd Water and were stretched to a maximum by attaching Weights to the end of each strand and suspending the strand. Each stretched about 8 percent. The strands were maintained in taut, stretched position and were immersed in a 1 percent pbenzoquinone solution at pH 8.0 for a 24 hour period. The strands were washed with tap water and dried over night. When analyzed, it was found that the p-benzoquinone content was 0.35% (weight).

EXAMPLE XIII The procedure described in Example XII, above, was followed-except for the stretching operationin treating wet, fresh, neutral hide. The quantity of hide used was 45 grams. The treated hide contains 0.17% (weight) of p-benzoquinone.

It will be understood that the process described above may be utilized in the preservation of other collagenous materials such as leather, the useful lifeof which is frequently shortened by the attack of micro-organisms and enzymes produced by such micro-organisms.

The method of treating collagen articles with polyhydric phenols and the products obtained thereby is claimed in co-pending application Serial No. 284,244 filed concurrently herewith as a continuationdn-part of application Serial No. 85,302, filed January 27, 1961.

While the invention has been described in detail according to the preferred method of carrying out the process and yielding the products, it will be obvious to those skilled in the art that changes and modifications can be made without departing from the spirit or scope of the invention, and it is intended in the appended claims to cover such changes and modifications.

What is claimed is: a

-1. In a method of tanning collagen that has been acid 5. The method of claim 1 in which said aldehyde is formaldehyde.

6. The method of claim 1 in which said aldehyde is glyoxal.

the group consisting of monocyclic, dicyclic and tricyclic quinones, and characterized by a chromium anal ysis from about 0.5% 'to about 1.5% .by weight chromic oxide.

12.'An aldehyde, quinone and chrome tanned collagen suture obtained by extruding'and reconstituting acidswollen collagen, said suture analyzing from about 0.25 to about 0.92% by Weight of p-benzoquinone, and characterized by a chromium analysis of from 0.5 tooabo'ut 1.5 by weight chromic oxide.

13. An aldehyde, quinone and chrome tanned collagen suture obtained by extruding and reconstituting acidswollen collagen, said suture analyzing from about 0.25% to about 0.92% by weight of 1,2-naphthaquinone, and characterized by a chromium analysis of from 0.5% to about 1.5 by weight chromic oxide.

14. An. aldehyde, quinone and chrome tanned collagen suture obtained by extruding and reconstituting acidswollen collagen, said suture analyzing from about 0.25% to about 0.92% by weight of 1,2-anthraquinone, and

- characterized by a chromium analysis of from 0.5% to 7. The method of claim 1 in which the collagen is in the form of a tape.

8. In a method of tanning collagen that has been swollen, extruded and reconstituted; the steps of con tacting said collagen with a solution of a quinone selected from the group consisting of monocyclic, dicyclic and tricyclic quinones, and subsequently contacting said collagen with a solution of an aldehyde and a basic trivalent chromium salt.

9. In a method of tanning collagen that has been swollen, extruded and reconstituted; the steps of contacting said collagen with a solution of an aldehyde and a basic trivalent chromium salt, and subsequently contacting said collagen with a solution of a quinone selected from the group consisting of monocyclic, dicyclic and tricyclic quinones. I

10. In a method of tanning a collagen suture obtained by extruding and reconstituting acid-swollen collagen; the steps of contacting said suture with an alkaline solution containing p-benzoquiuone and subsequently con tacting said suture with an aqueous solution containing about 0.32 part of formaldehyde, about 1.0 part of chroing a pH of about 3.5.

. 11. An aldehyde, quinone and chrome tanned collagen article obtained by extruding and reconstituting acidswollen collagen, said article analyzing from about 0.25% to about 0.92% by weight of a quinone selected from mium III sulfate calculated as chromic oxide, and havabout 1.5% by weight chromic oxide.

References Cited in the file of this patent UNITED STATES PATENTS 1,985,439 Blackadder a. Dec. 25, 1934 2,164,101 Adams June 27, 1939 2,191,943 Russell et a1. Feb. 27, 1940 2,401,373 Robinson June 4, 1946 2,475,697 Cresswell July 12, 1949 2,521,738 McMeekin et a1 Sept. 12, 1950 2,552,129 Windus- May 8, 1951 2,552,130 Windus May 8, 1951 FOREIGN PATENTS 10,460 Great Britain Mar. 10, 1909 of 1909 I OTHER REFERENCES OFlaherty et al.: The Chemistry & Technology of Leather, Vol. II, pub. by Reinhold Pub., 1958, pages 91- 94, 254-255, 261, 267 and 273-275.

McLaughlin et al.: The Chemistry of Leather Mann facture, A.C.S. Monograph Series, Reinhold Pub. Corp., 1945, pages 388-410, 503, 568, 584, 585 and 586, pages 389 and 403-406 are especially pertinent.

Chen: Syntans and Newer Methods of Tanning, The Chemical Elements, South Lancaster, Mass., 1950, pp. 87- 96. 

1. IN A METHOD OF TANNING COLLAGEN THAT HAS BEEN ACIDSWOLLEN, EXTRUDED AND RECONSTITUTED; THE STEPS OF CONTACTING SAID COLLAGEN WITH AT LEAST TWO DIFFERENT SOLUTIONS, OND OF SAID SOLUTIONS CONTAINING A QUINONE SELECTED FROM THE GROUP CONSISTING OF MONOCYLOC, DICYCLIC AND TRICYCLIC QUINONES, AND ANOTHER OF SAID SOLUTIONS CONTAINING AN ALDEHYDE AND A BASIC TRIVALENT CHROMIUM SALT. 